Various types of waste materials, such as food waste, industrial waste and garbage are disposed of by drying to reduce moisture and incinerated, or deposited directly as landfill. Significant environmental contamination often results from production of dioxins, carbon dioxide and nitrogen oxides. Landfill sites leach toxins such as heavy metals into surrounding ground water tables and organics convert into gases such as methane which pollute the atmosphere.
U.S. Pat. No. 4,872,993 discloses a method for treating waste water comprising adding clay and a flocculating agent to waste water which absorbs organic matter and heavy metals in the waste water to form a sludge separating the sludge from the water to reduce the water content to less than 60% by weight, and firing the sludge at a temperature of about 2000° F. to convert sludge particles to expanded ceramic particles. The solid residue powder can be heated to above about 200° C. and subjected to microwave energy at a wave energy frequency effective to decompose and depolymerize the resin. Alternatively the solid residue can heated to about 400° to 750° C. in an oxygen free atmosphere to depolymerise resins and to produce gaseous hydrocarbons, the hydrocarbons separately recovered, and the solids residue sintered at a temperature of about 750° to 1150° C. to produce chemically inert agglomerates.
U.S. Pat. No. 5,490,907 discloses a method for recovery of organic volatiles from an organic sludge containing 20 to 99% by weight solids in which clay powder is added and the mixture heated to about 350° C. in a distillation vessel to distil the volatiles and produce a granular solid residue. The solids residue can be used as an inert, environmentally safe raw material such as in the cement industry or recycled for use in the process as a reagent powder.
There is a need for treatment of a wide range of waste materials including sewage, garbage, construction and industrial waste and the like to minimize landfill and atmospheric pollution.